There is an "Undefined offset: 0 in media_add_upload_submit() (line 140... in media/includes/media.pages.inc" when you are using the workbench_media module to upload a file though the media_add_upload_form.

The $params = $form_state['build_info']['args'][0]; never checks if the the form_state build info is set or not and there is nothing in the following code that requires it to be set so we need to add a isset() around it.